According to the arrangement of the shaft roller and the position of the adjusting roller, the multi-roll straightener can be divided into: upper and lower roller parallel straightening machine, upper and lower roll tilting machine.

The basic method of finding a plane intersecting line is as follows: ridge surface method and ridge line method.

Q: Hot riveting is usually made up of four people. What is their division of labor?

A: One person to heat, pass, one to pick up rivet, one to prop up the rivet, one person riveting.

Q: What is the effect of the flat end of the taper shank drill?

A: Used to increase the transmission of torque to avoid drilling knock out in the main shaft hole or drill sleeve.

Q: What is the function of the guiding part of the drill?

A: During the cutting process, it can keep the drilling direction of bit integrity. At the same time, it has the function of repairing the hole wall, and it is also the backup part of the cutting part.

Q: What are the undesirable phenomena that occur when the hole is about to be drilled?

A: Due to the sudden recovery of mechanical clearance and elastic deformation of drilling machine, the axial resistance suddenly decreases when the drill is drilled through the workpiece, and the drill will be automatically cut in with a large amount of feed. As a result, the drill bit is broken or the drilling quality is reduced.

Q: What is the effect of cutting fluid when drilling?

A: Reducing friction, reducing bit resistance and cutting temperature, improving the cutting ability of the drilling bit and the surface quality of the hole wall.

Cutting amount: It is the generic terms of cutting speed feed and cutting depth.

Grinding: it is the method to process the surface of workpiece with grinding wheel.

Expansion: the process of spreading the surface or part of a metal structure on a plane in order of its actual shape.

The way to draw the unfold graph include: parallel line method, triangle method, radiation method.

The expansion condition of the parallel line method is: the elements on the surface are parallel to each other and reflect the actual length on the projection surface.

Plate thickness processing includes: determine the neutral layer of the bending part and eliminate the thickness interference.

The neutral layer position change of thick plate is related to sheet bending radius and sheet thickness.

The general principles for the thickness treatment of the intersecting plate are: the expansion length is based on the dimension of the neutral layer. The curve height in unfold drawing is based on the contact height in the position of structural steel connection part.

The main contents of lofting are: the plate thickness processing, the expansion of the drawing and to expand the drawing of the marking sample according to the made components.

The expanded sample can be used for: marking, manufacturing and separation of molds and milling sample.

Edge attenuation: In the molding process, the edge material of the deformation part is stretched thin. The forming method include press and pull.

Pull out edge: The edge of the plate is machined into curved workpiece by means of the pulling edge and closing edge.

Roll edge: to increase the rigidity and strength of the edge of the workpiece by curling the edge of the workpiece.

Close seam: the edge of the two sheets or the two sides of a piece of plate are combined to squeeze each other, which is called a close seam.

Plate thickness processing: the method adopted to eliminate the effect of plate thickness on the shape and size of the expanded graph.

The general steps for calculating the expansion length of the bending parts are: divide the bending parts into straight and circular segments; calculate the length of each segment separately; add the calculated length.

Q: When the external force is removed, what is the cause of the rebound?

A: Because of the surface of the sheet is subjected to pressure on the inner surface during the manual bending, so the rebound is generated.

The cold arch is obtained through the edge of the shrinking sheet. The hot arch is obtained through heating of plate to shrink the sheet.

There are two ways to pull the edge, one is to use the universal tool to pull the edge, one is to use the forming mold.

Closing edge: the closing edge is to make the plate wrinkly first, and then flatten the wrinkling position to prevent stretching recovery. In this way, the shrinkage length of the plate is reduced and the thickness is increased.

The basic principle of closing edge is: for the forming of convex curved edge workpiece, it is mainly that the outer edge material of curved plane is shrunk and thickened and shortened, forcing the vertical edge to curve.

The purpose of correction is: by applying external force or local heating, the longer fibers are shortened and the shorter fibers are elongated, and the fibers of each layer tend to conform to the correct purpose.

The principle of flame correction is: the original deformation is offset by the deformation of the metal part by heating to achieve the purpose of correction.

The heating method of flame correction is: dot, line and triangle heat.

The factors determining the technological margin are: the influence of sample error; the influence of errors in the machining process of parts; the influence of assembly error; the influence of welding deformation; the effect of flame correction.

According to the application, the sample can be divided into: marking sample, molding sample, positioning sample and spline.

A: based on two perpendicular lines or faces; take two center lines as the baseline; based on a plane and a central line.

Lofting allowable error: in the process of lofting, there will be a certain size deviation in the real sample due to the influence of the release gauge and tool precision as well as the operation level. This deviation is controlled within a certain range, and the error is called lofting allowable error.

The structure lofting includes: determine the location and connection form of each department; make necessary changes according to actual production and processing capacity; calculate or measure the actual length of part material and shape of plane parts; design the mold or mold frame.

The method of rectifying the line segment is as follows: rotation method, right triangle method, change surface method, branch line method.

Q: What is the rule of drawing with a right triangle to calculate the length of the line segment?

A: it is the projection of a line segment on any projective plane as a right angle of a right triangle. The projection length on the vertical axis of the plane is the opposite of the angle. The hypotenuse is the length of the line segment.

Rotation method calculates the actual length: it is the general position of the space around a fixed axis rotating into parallel lines, the projection of the line on the projective plane parallel to it reflects the real length.

Changing surface method: it is to set a new projection plane parallel to the curve, and the projection of the curve on the surface reflects the real length.

Expansion method: stretch a length in the curve view, while maintaining the height in the other view, the expansion line is the desired result.

The basic features of the intersecting line are: the intersecting line must be a plane figure enclosed by a closed line or curve; the intersecting line is the common line between the plane and the solid surface. It’s a collection of points that are both on the plane and on the surface.

The method of finding the vertical intersecting line is: ridge surface method and ridge line method.

The method of calculating the intersection line of the curved surface is as follows: tessellation lines method and latitude line method.

The essence of the intersecting line is: to find a certain number of common points on the surface of the two bodies, connecting these common points in turn is the desired result.

The principle of intersecting line choosing method is: a projection of the intersecting line at least one known intersecting line by the tessellation line method. The intersection line should be the simplest geometric figure calculating with the auxiliary plane method. The spherical method is only suitable for the rotating body and the component that intersects the axis.

Q: Under what conditions, the intersecting line is a plane curve? The positive projection of the curve is the intersection of two straight lines?

A: The intersecting line is the plane curve when the two outer edges are intersected in the same sphere. At this point, when the axis of the two rotating bodies is parallel to the basic projective plane, the projection of the intersecting line on the plane is two intersecting lines.

Straight grain surface: it is a surface formed by a straight line.

Q: What are the features of the cylindrical surface?

A: All the tessellation lines are parallel to each other. The cross-section of the section graphics is the same when cut the cylindrical surface with a parallel plane.

Q: What are the characteristics of the cone?

A: All the tessellation lines intersect at one point. The cross section of the cone is similar when cutting the cylindrical surface with a parallel plane. The intersecting line at the top of the cone is a triangle.

The plastic deformation process of materials is divided into: material bending; the material is stretched and deformed; added stretch.

Stretch forming: the plate is subjected to plastic deformation according to the ideal surface under the tensile condition, and overcome the springback. This forming method is stretch forming.

Plate thickness processing includes: determine the neutral layer of the bending part and eliminate the thickness interference.

The change of neutral layer position of plate thickness is related to sheet bending radius and sheet thickness.

Rebound: in bending process, when the external force is removed, the response of the material due to elasticity is called rebound.

Drawing: a punching process method for making hollow parts of sheet material by using press and corresponding molds.

Stretch coefficient: the ratio of the area of the material after each stretch to the area before stretching is called the tensile coefficient. The stretch coefficient actually reflects the degree of deformation of the tensile part.

The working principle of friction press is: use the contact drive of flywheel and friction disc and work with the relative motion principle of screw and nut.

Q: What are the advantages of friction press?

A: Fast movement, can make the slider stop at any position in the stroke. Once overloaded, only cause the sliding between the flywheel and the friction disc, without damaging the machine.

Q: What are the advantages of the stamping process?

A: （1）High production efficiency. One stroke of the press can complete a process, and sometimes many processes can be completed.

（2）High material utilization ratio.

（3）The shape and size of the stamping parts of the same product are the same and the interchangeability is good.

Blanking: a stamping method used to separate sheet material by the press.

Q: How to distinguish hole punching and blanking?

A: In general, the sheet material is blanched to form two parts, that is, the blanking part and the perforated part. If the target of cutting is to make a certain appearance of the workpiece, that is, the blanking part of the need is called the blanking. On the contrary, the target of cutting is to process the inner hole of a certain shape, the falling part is the waste, called hole punching.

Q: What are the stages of separation of materials during the blanking?

Q: Horizontal rolling machine has three axis and four axis, three axis include which two kinds?

A: Symmetric and asymmetrical.

Q: For symmetrical triaxial rollers, what shape are the roll core of three rollers?

A: Isosceles triangle

When the material is rolling, adjust the distance of the roller so that the center of the roller must be kept parallel to each other, otherwise the workpiece will produce taper.

When the tube is bent, the material in the outer layer of the neutral layer is subjected to tensile stress, which makes the wall of the tube thin, and the pressure of the material on the inside makes the wall thicker.

When the tube is bent, because the section is circular and the stiffness is insufficient, it is very easy to crush deformation when bending in the free state.

When bending a billet, the pipe seams should as close to the center layer as possible.

The bending part of the bending tube must be subjected to pressure test to check for leakage.

Q: How to eliminate the straight head of the asymmetric three-roll roller?

A: The workpiece rolled out by asymmetrical triaxial rollers has straight head only at the beginning of the plate, as long as the workpiece is rolled over, turn the workpiece rolling over again, the straight end of both ends can be eliminated.

Anti-deformation method: it is the tube billet that presets a certain amount of deformation on the outside of the pipe wall to offset or reduce the deformation of the section when it enters the bending deformation zone.

In the small batch or single piece assembly t-shaped beam, generally take the line drawing assembly.

The assembly speed can be further improved by adopting mold assembly when assembly of the t-shaped beam and the I-shaped beam.

Q: The longitudinal shrinkage of the weld joint decreases with the increase of weld joint length, right?

A: no

The railings of the bridge crane are truss structure with the same arch degree as the main beam.

Q: Box beam, bridge, and frame also should have certain camber, the upper arch of the part should be greater than the allowable deflection of the beam, right?

A: no

Due to the self-weight of the bridge and the influence of welding deformation, the camber of the box girder webs should be greater than the upper camber of the main girder.

When the steel plate is thin and the weld is in the middle of the steel plate, wave deformation often occurs after welding.

When the welding parts cannot overcome the shrinkage of the weld, the deformation of the welding body is caused.

When the line is parallel to the projection plane, it is called the parallel line of the projection plane. The projection of the line is true.

Any metal sheet has a thickness, and plate thickness has an effect on the shape and size of the expanded graph.

For the component with a sphere, circle, or helix surface, the surface is undevelopable.

For the expansion of prism and cylinder, parallel line expansion is generally applied.

The conical tube is intersected with the cylindrical tube, and its intersecting line is often obtained by the auxiliary plane method.

The calculation of the length of curved line always uses expansion method.

The stroke of the slide block of open crank press can be adjusted by changing the center distance between the eccentric sleeve and the main shaft of the upper part of the connecting rod.

In the deep drawing, extrusion process, due to the gap of the mold, the requirement for the thickness tolerance of materials is strict.

The lower the depth coefficient, the greater the deformation degree of the material.

Cold stamping: the stamping process at room temperature is called cold stamping.

Compound procedure: combine two or more basic processes together, complete in one stroke of the press, called compound process.

Simple blanking die: in one stroke of the press, only one blanking process can be completed.

Composite blanking die: under one stroke of the press, multiple processes can be completed simultaneously.

Q: How to explain the blanking force correction factor Kp?

A: the safety factor selected when calculating blanking force, consider the wear of the cutting edge, the gap of the mold, the mechanical properties of the material. In general, Kp is equal to 13.

Inclined edge cutting: a method to reduce blanking force. When the cutting edge is made into a slanting Angle, the contact between the cutting edge and the blank is gradual, so that the load is uniform and smooth.

Stepped punch blanking: a method to reduce blanking force. In the simultaneous blanking, the punching head is made into a ladder form against the billet, which can effectively disperse blanking force when blanking.

Q: What is the difference between open crank press and closed crankshaft press?

A: In the structure, the bed of the open crank press is a c-shaped structure, and the rotary motion of the eccentric spindle is converted into the upper and lower reciprocating motion of the sliding block by the connecting rod. The frame structure of the closed press is replaced by the crankshaft.

Q: What are the characteristics of open crank press and closed crankshaft press?

A: Open crankshaft press C – shaped bed with three sides open, especially suitable for large sheet metal edge stamping processing. However, this form of bed structure itself is less rigid, so it can bear less load. The frame structure of the closed crankshaft press is limited by the column, the working table area is limited, and the operation space is small, so there are certain restrictions on the surrounding size of the stamping parts. The frame structure is rigid and the load is large and uniform.

A: if the gap between convex and concave die too small, the crack of the materials near to the blade stager a certain distance, so, the materials between the upper and lower grain impact the cross section quality by the second cutting as the blanking process continues. When the gap is too large, the crack of the material near the edge of the convex mold is staggered at a distance, and the material is greatly stretched. Burrs on the edge of the material, the collapse angle and the slope are larger, which also affect the section quality of the blanking pieces. In addition, the clearance is too small or too big, the size deviation of the offset has certain effect.

Q: What are the factors that affect the minimum bending radius of the material?

A: 1) mechanical properties and heat treatment of materials.

2) bending angle of the workpiece.

3) the geometry and size of the material.

4) bending direction

5) other aspects, such as material thickness, surface and side quality, etc.

The neutral layer of the material during bending is: In the bending process, the outer layer is stretched and the inner layer is extruded. There is bound to be a transition layer that is neither tensile nor pressurized, and the stress is almost zero. This transition layer is called the neutral layer of the material.

When the component of the multi-beam column is corrected, the joint relation between the beam column should be fully considered.

In correcting the deformation of the sheet in the steel structure, it is necessary to ensure that all kinds of frames meet the requirements, and then we can consider the correction of the thin plate.

The hot spot of point heating is related to the thickness of plate. The distance between hot spots should be uniform.

Q: How is internal stress produced in steel structural parts?

A: The welding process is an uneven heating and cooling process for the welding structure, which is the main reason for the internal stress in the welding structure. In addition, all parts of the steel structure may have residual stresses after their billet state or processed into parts. After being welded together, these residual stresses may be assembled into new internal stresses.

Q: What are the factors that affect the welding deformation of steel structure?

A: Design and process. The design refers to the rationality of structural design, the position of the weld and the form of welding groove. The process refers to the reasonable welding procedure, the welding sequence, the use of various anti-deformation and anti-deformation methods, and the measures to eliminate the stress.

Q: How to understand the inner connection of steel structure?

A: The steel structure is connected by welding, riveting or connecting bolts. These parts are interconnected and mutually restricted to form organic integrity.

Q: What is the main point to rectify the deformation of steel structural parts?

A: 1. Analyze the causes of deformation of the components, and find out whether the deformation is caused by external forces or the deformation caused by internal stresses.

Analyze the internal relation of the components, and find out the restriction relationship between each component.

Choose the correct correction part, solve the main contradiction first, and then solve the minor contradiction.

To understand and master the properties of the steel used in the component, so that the workpiece can be broken, crack or rebound, etc.

To determine the correct method of correction, and the sequence of various methods.

For sheet deformation in steel structure, only local heating (and point heating) can be used for correction.

Q: What should be paid attention to when the thin plate deformation is corrected by point heating?

A: 1.the heating temperature should be appropriate, which should be enough to cause the plastic deformation of the steel, and the temperature should not be too high, generally 650-800℃.

add hot spots and the distance between points and points should be appropriate. In general, depending on the thickness of the plate, the arrangement should be even, and more plum-shaped layout.

The purpose of watering the cold and hammering is to accelerate the shrinkage of the steel plate.

4: when heating, the gas welding torch should not swing back and forth, the small flame should be a vertical steel plate, and the hot spot should not be too much, so as not to increase the internal stress.

Q: What are the characteristics of the deformation of frame components?

A: There are many parts of frame components, which have a strong mutual restriction in the structure, and the deformation has great influence on each other.

Q: When the rolling machine rolls, it is usually done after heating, right?

A: no

For heating bend, material should be heated to 950-1100 ℃.

Heat evenly at the same time, the temperature is not lower than 700 ℃ at the end.

The possible defects when rolling the cylinder: the defects that may occur when the cylinder is rolled are distorted, the curvature is different, the curvature is too large, and the middle drum is shaped.

When rolling the cone, the center of the upper axis is adjusted to a tilt position, and the axis of the roller is always coincident with the generating line of the fan-shaped blank, so that it can be rolled into a cone.

When the cone is rolled, the friction force of the billet is increased, so that the speed of the small mouth is lower than that of the big mouth.

There are a lot of axial forms, including round head type, pointed type, hook type, unidirectional joint type, and universal type.

The non – core bend do not use the core axis. The deforming process is used to control the deformation of the bending tube.

When the bending radius of the tube bend is 1.5 times greater than the diameter, it is generally adopted bending method without the mandrel.

The bending tube is made of metal plasticity. Under normal temperature, the tube is pressed into a curved mold to form a pipe bend.

When the bending tube is pressed, it is also affected by the axial direction and the opposite force of the axial force.

Q: Description of rolling machine rolling billet process?

A: For roll bending, place the metal plate between the roller of rolling machine. The rotation of the roller and the friction between the roller and metal plate making the plate moving, thus constantly forming bending shape.

The advantages of the four- roller rolling machine are: the two ends of the sheet can be rolled to eliminate the straight edge on both ends. It simplifies the process, reduces the workload and improves the production efficiency compared with 3 roller rolling machine.

A: In the curved pipe, in order to reduce the cross section ovality, it is often used to fill material in the pipe, or the roller of the cone groove is pressed outside the pipe, or the mandrel is used to bend in the process of production,.

Q: What are the advantages of spool mandrel?

A: Spoon type mandrel and outer wall supporting surface are large, the anti – flat effect is better than the tip type, the surface is not easy to wrinkle during the pipe bending. Spoon – type mandrel manufacturing is also convenient, so it is widely used.

Q: What are the advantages of tube bending with mandrel than that without mandrel?

A: (1) reduce the preparation of mandrel before bending the pipe, thus improving the production efficiency.

(2) avoid the manufacturing of the mandrel and reduce the cost.

(3) no lubrication is needed in the pipe, which saves lubrication and oil injection.

(4) ensure the quality of the elbow.

(5) there is no friction between the mandrel and the pipe wall, which reduces the torque of the bending tube, thus extending the service life of the pipe bender.

Q: How does the mechanical pipe bender drive?

A: Driven by the motor through the gear shaft, decelerate mechanism, worm gear and worm drive, to drive the bending die.

Q: The transverse distance and high and low position of each pair of roller is not the same when assembling the circular seam on the roller stand. In this way, the cylinder can be concentric, right?

A: no

Q: If there is a deviation in the diameter of the two cylinder sections, the larger diameter cylinder should be blocked up during the assembly to make the two sections concentric, right?

A: no

The larger the linear expansion coefficient of welding material, the larger the shrinkage of welding seam.

Q: The shrinkage of carbon steel is greater than that of stainless steel and aluminum, right?

A: no

Q: When using hammer weld to prevent multi-layer welding deformation, the hammer should be applied on the first and last layer, right?

A: no

Q: Rigid fixed method can cause great internal stress in weld area, so this applies to medium carbon steel and alloy steel, right?

A: no

A lever and screw tensioner are often used to assemble the longitudinal seam of the cylinder to improve assembly efficiency.

The radial push brace is often be used to adjust the ellipticity of the thin wall cylinder.

When the elongated cylinder joints are connected, the assembly can ensure that the whole frame is not bent.

When assembling the circular seam of the cylinder, the clamping device can be used to clamp and align the circular seam, which can achieve a better effect and obtain the needed clearance.

When mounting the cylinder ring seam, use the retaining iron for positioning.

Finally, use the circle wedge clamp.

The rivet gun is mainly composed of hand, gun body, trigger, pipe joint and so on.

Before cold riveting, it is necessary to improve the plasticity of materials to eliminate hardening.

The core rivet is composed of hollow rivet and mandrel.

After the weld is cooled, it produces a contraction in the weld area, which causes internal stress in the welding body.

In multi-layer welding, the first layer causes the largest contraction, the second layer is about 20% of the first layer shrinkage, and the third layer is about 5% to 10% of the first layer.

Pull riveting: pull riveting is another kind of riveting. It is powered by hand or compressed air and riveted by special tools.

Hot riveting: riveting after heating.

Anti-deformation method: the direction and size of the deformation after welding is analyzed. Before welding, the welded parts should be made of the same size and opposite deformation to offset or compensate for the deformation after welding, so as to prevent deformation after welding.

Rigid fixing method: use the assembly fixture or temporary support to fix the welding joint position to prevent deformation after welding.

Q: The lofting diagram is the drawing according to the construction drawing, right?

A: no

The developable surface not only include the plane, but also the cylindrical surface and the cone surface.

All the graph lines on the expansion diagram are the real long lines of the corresponding parts on the surface of the component.

Q: If the line segment has a projection of a three-plane projection has accumulative features, then the other two projections must be true, that is, the response line segment is real, right?

A: no

Q: The two-sided projection of the line segment is perpendicular to the projected axis of the clamping, and the projection of the third plane must be the length of the line segment, right?

A: no

Q: The projection of a straight line is always a straight line, there’s no other case, right?

A: no

The general position line in the three view, sometimes reflects the actual length, sometimes not.

Q: For the real length of the line in general, it’s better to use the rotation method, right?

A: no

Q: The way to find a line segment is the parallel line method, the triangle method and the radiation method, right?

A: no

In the production of riveter or sheet metal work, the drawing is commonly used in the right angle triangle method, the rotation method, changing face method and branch line method.

Q: When you expand the form with a triangle, the key is to figure out the actual length of each tessellation line, right?

A: no

Q: The plane curve always reflects the real length in the three views, right?

A: no

Prism, cylinder and cylindrical surface can be expanded with parallel lines method.

Q: The triangular expansion method applies to the expansion of all the tessellation lines at the surface of all components intersect at one point, right?

A: no

Q: When the intersecting line is obtained by the auxiliary method, the axis of the rotating body is parallel and reflect the real length, right?

A: no

The press used by riveters is: hydraulic press and pneumatic press.

Q: How does the final riveting temperature affect the riveting?

A: Too high will reduce the initial stress of the nail rod; too low, the rivet will generate the blue brittleness phenomenon.

Q: How does the shank of the drill work?

A: The torque and axial force required to hold and transfer the borehole.

A: Reasonable choice of cutting amount can prevent premature wear or damage. Prevent the machine from overloading and improve the cutting precision and surface roughness of the workpiece.

Thread tapping: cutting internal threads with a tap on the hole wall.

Q: How does the diameter of the bottom hole affect the tapping?

A: If the diameter of the bottom hole and the diameter of the internal thread are the same, the material will be stuck in the tap, and the tap is easily broken. If it is too large, it will not tapping enough height of the thread tooth profile, which will form a waste product.

Thread chaing: cut out of the thread on the outer diameter of the round pipe with the thread die.

Q: What principles should be paid attention to when choosing groove?

A: (1) minimize weld metal filling.

(2) ensure penetration and avoid cracks.

(3) consider minimum welding deformation.

(4) easy to process.

A blunt edge can be used to prevent the joint from burning through the open groove.

Carbon arc gouging: using the high temperature of the carbon arc to melt the parts of the metal, and then blow the molten metal off with the air of compressed air, to achieve the purpose of planing or cutting the metal.

Grinding can eliminate the burr on the edge of the plate, repair the weld, and polish the weld before inspection of the pressure vessel.

Bending forming: to bend a slab, profile or pipe to a certain angle, curvature, to form part of a certain shape.

Rebound phenomenon: elastic deformation occurs when bending. When the external force is removed, some elastic deformation is restored to the original state, and the shape and angle of the bending parts are changed.

The bending methods used for riveting are: bending, rolling, pressing and line heat forming.

The factors that affect the shape change of section in the bending process are relative bending radius, geometrical characteristics of section and bending mode.

Q: What is the effect of steel heating on the bending process of steel?

A: The bending force is reduced after the steel heating, the elastic phenomenon disappears, the minimum bending radius is reduced, and the deformation is controlled according to the processing requirement.

Q: Why should the steel heating temperature be limited to a certain temperature?

A: Too high temperature can cause steel to overburn, too low temperature can make molding difficult, and cause cold hardening.

Q: When using contact bending, what measures are used to solve the problem of springback?

Press bending: the process of using bending mold on a press machine to do bend forming.

Q: Why do riveters usually use press mold with welding structures?

A: Because this not only makes convenient but also can shorten the model period, improve material utilization rate, reduce cost.

Larger workpiece rolling: in order to avoid the additional deformation caused by its gravity, the plate should be divided into three regions for rolling. Roll two sides first, then roll the middle, if necessary, use the crane.

Non-cylindrical workpiece rolling: according to its different radius of curvature, the area should be divided on the plate, and the roller spacing should be adjusted.

Before the workpiece is rolled, the roller and sheet should be cleaned and burr removed to avoid damage to the workpiece and roller.

Pressing: to form an open hollow part through a concave die under the pressure of a convex mold.

Line heat forming: the steel plate is partially heated and shrunk by oxyacetylene flame.

Line heat forming is only suitable for parts with small curvature, and more is combined with rolling pressure to process parts with double curved complex shapes.

Line heat forming method: shape heating and point heating. The process include: the selection of the roasting nozzle, heating temperature and heating rate, cooling mode.

Line heat forming cooling method: air cooling and water cooling. Water cooling is divided into front water cooling and back water cooling.

Air cooling: When the flame is heated locally, the workpiece cools naturally in the air.

Water cooling: the metal that has been heated partly by the use of water to cool it quickly, reduces the heat transfer to the back, enlarges the temperature difference between the front and the back, and improves the molding effect.

Q: What are the characteristics of explosive forming?

A: The mold structure can be simplified; the machinable shape is complex, the rigid die hard to process hollow parts; small rebound, high precision and good quality; fast processing molding speed; no stamping equipment is required.

Angle connection: when the two plates are connected perpendicular to each other, they are riveted together with angle steel at the joint.

The main parameters of the rivet are rivet pitch, row spacing and margin. Rivet pitch: the distance between two adjacent rivet in a row of rivets. Row spacing: the distance between two adjacent row of rivet holes. Margin: the distance from the outside rivet center to the workpiece plate.

Q: What is the relationship between the thickness of the component plate and the diameter of the rivet?

A: When the single row and double row are connected, the diameter of the rivets is twice the thickness. When the single row and double row double cover plate is connected, the diameter of the riveting is 1.5~1.75 times the plate thickness.

The principles for determining plate thickness are: during lap joint, determine according to plate thickness. When the material with big different thickness is riveted, it is determined by thinner plate. When the steel plate is riveted with the profile, the average thickness of the two is taken. The total thickness should not exceed 5 times of the rivet diameter.

Q: What is the relationship between rivet length and riveting quality?

A: If he rivet is too long and the head of the rivet will be too large, the rivet rod can be easily bend. If the rivet is too short, the piers are not large enough, the rivet head forming is incomplete.

The rivet is too short, the piers are not large enough, the nail head is incomplete.

In cold riveting, the rivet rod is not easy to heading. In order to ensure the connection strength, the diameter of the rivet hole should be close to the diameter of the rivet rod. In hot riveting, the diameter of the rivet hole should be slightly larger than the diameter of the rivet rod due to thermal expansion and thickening.

Rivet consists of hand, gun body, switch and pipe joint.

Q: What are the features of the riveter?

A: Small size, easy to operate and can be riveted in various positions.

Riveting can be divided into cold riveting and hot riveting. Cold riveting is the riveting at room temperature. The final hot riveting temperature is between 450 ~ 600 ℃.